eckert



(No Model.) 2 sheets-sheen 1.

W. H. ECKERT.

TELBPHGNIC TRANSMISSION. No.l 292,212. Patented Ja l. 22, 1884.

5 L WLULMLEEc/ce rf (No Model.) 2 Sheets-Sheet 2. W. H. ECKERT.

TBLBPHONIG TRANSMISSION. N0.`292,212. Patented Jan. 22, 1884.

- removing the primary electrical source.

VLLIAM H. ECKERT, OF EV YORK, Y.

TELEPHONIC TRANSil-JliSSiN.

SPECIEKCATION forming part of Letters Patent No. 292,212, dated January 22, 1884. Application filed December 4, 1882. (No model.)

To all whom, t may concern.-

Be it known that I, WILLIAM H. Ecitnn'r, oi' the city, county, and State of New Yori and a citizen of the United States oi America, have made a new and useful improvement in the art of long-line telephonie transmission, which consists in the method of and means for overcoming the effects ofstatic induction arising upon the main line.

Vhen an electrical impulse is thrown upon aline ruiming in close proximityto the earth, owing to an electrical reaction between the line and the earth, the-transmission of the im pulse from one point of the circuit to another is retarded, and a considerable electricity is stored in and about the line, which will escape if the line is connected to earth upon It the primary 'source oi' electricity be removed from the line, and the remote ends of said line are connected to earth, an inductive discharge will occur upon the line from its center toward both ends. The inductive dis charge at the receiving-station is a secondary current of the same direction as and closely following the primary current.

At the transmitting` end ot' the line the current of inductive discharge is a quick current running fro mthe center ofthe li ne in a direction opposite to that ofthe primary current. These currents occurring` at the two grounded er;- tremities ot' a line l terni, respectively, the counter and tailing currents of inductive discharge, and i'or convenience of description I term them the eifects oi' static induction.77

In the process of telephonie transmission electrical impulses of variable strength suc ceed one another with great rapidity. In case telephonie transmission is eiiected by iinpulses all oi' one polarity, each succeeding impulse in the iirst half of the circuit is met and weakened by the counter current of in duetive discharge due to the preceding impulse, while each succeeding impulse will so closely follow the tailing current of the preceding impulse that they will either be blended or the space separating the two primary impulses will be nearly filled by the tailing current. It telephonie communication is eiieeted by impulses alternatelypositive and negative,

as is generally the ease, the tailings of a preceding impulse, at the receiving end ofthe line,will meet and partially neutralizethesuc cecding impulse, the polarity oi" the succeed ing primary impulse being opposite that of the preceding. The tailing current, as well as the countercurrent, in point of quantity and duration, depends upon the length of the line. Thus, it' the length ofthe line be so great as to ati'ord a tailing current which will cause the blending ot' one impulse and a succeeding one, transmitted speech will lose its characteristic ot' articulate sound, and the counter-current will be so great as to materially weaken the primary impulses upon which loudness ot' reproduced sounddepends. Therefore, ii the counter and tailing currents must wholly escape at the two extremities of the line, the limit oi" line-length upon which telephonie transmission can be practically et! fectcd is soon reached.

To the end oi' enabling telephonie transmission upon lines ot' great length, ll provide means i'or inductive discharge from many intermediate points along its length to earth, which consists in establishing permanent leal;- branehes ot high resistance. 3y this means the inductive discharge of the section between two adjacent leali-branches occurs independ cntly ot' the inductive discharge of the other sections, and, however long a line may be, the time and magnitude of the inductive discharge will depend only upon the length ot' its sections. Obviously, the shorter the mainline sections between lealcbranches are the less will be the interi" Tence trom inductive currents.

I have ascertained that when employing lealcbranches, which are formed as hereinafter specified, the best results are attained by employing leali-branches distributed over the line at a distance ot' about one-third of a mile apart, in which case they may be or" a suiiiciently high resistance as not to cause atoo great leakage of the primary impulses, while they permit the ready escape from line of the currents of inductive discharge. Leaks ot' less resistance more widely separated, as-by two or three miles, maybe used; but the inductive discharge from each section would be Slow and the quantity large, even if the leal'- resistance were so small as to divert the greater portion of primary impulses from the main line.

I have discovered that a series of leakbranehes distributed along a line whose joint resistance is far greater than the resistance of a single leak-branch will free the line more readily of inductive-diseharge currents than the single leak,`and at the same time they will not canse as great .veakening of the main-line current. Ten leak-branches, whose joint resistance is t-hree hundred thousand ohms, I iind will more eftlciently free the line from iuductive currents than a single leak of one huudred thousand ohms, and the leakage from line in the former case is only one-third as much as in the latter.

The means which I prefer for providing leaks when they are placed about one-third of a mile apart' consist of an iron or other metallie pin set in or attached directly to a wooden telegraph-pole or a cross-arm thereof, and without the intervention of insulating material; or the pole and cross-arm may be of other material of high resistance; or, instead of supporting the line-wire directly upon a cross-arm, the wire may be supported by an intervening glass or other insulating support and joined to earth by any ordinary conductor containing a high resistance.

I will now describe my invention by reference to the accompanying drawings.

Figure l shows abattery telephonic transmitter, a magneto-receiver, and a main line provided with a series of leak-branches. Fig.

2 shows a main line and means of establishing the leak-branches. Figs. 3 and 4 show details of the iron-pin supports and lightning-arresters.

In Fig. l, T is an ordinary contact or battery transmitter. B is a battery in a local circuit, embracing the primary of the induction-coil I. S is the secondary of the induction-coil I in the main line L. R is a magneto-telephonie receiver, and a b c d e are a series of leakbranches connecting the line to earth at intermediate points of its length.

Fig. 2 represents a line, L, supported by a glass insulator, G, mounted upon a pin, E, which is placed upon an ordinary cross-arm, A, and the arm A is supported upon a telegraph-pole, II. In the same figure I-Iis an ordinar-y wooden telegraph-pole. A is a wooden cross-arm, and F is an iron pin supported in the cross-arm, without the intervention of insulating material, to which the line-wire is directly connected. An earth-branch from the line L is therefore established directly through iron pin F, cross-arm A,vand pole H.

Instead ofestablishing aleak-branch through the cross-arm and pole, the line-wire L may be supported upon a glass hood, and an earthconnection may be effected through a branch line, as O, having a rheostat, R71, of high re- 5 sista-nce.

detail. Said piu is hollow, and in its lower end is iitted a stopper or plug of insulating material, to which is attached a metallic piece, V, connected directly to earth by wire IV. V is insulated from the iron pin F, and serves as a lightning-arrester.

A lightning-arrester must be employed upon every pole where the line is in direct contact with the pole, as it would otherwise be shattered by lightning.

Instead of employing an iron pin, F', as shown in Figs. 2 and 3, I may mount a crosspieee, J, having two wire-supports, Q Q, of tube-iron, upon a tube-iron shank, FQ in the lower end oi' which is iitted the insulating-plug K, carrying the lightning-arrester V, to which is connected wire IV, and the iron shank F may be set directly in the wooden telegraphpole or upon a wooden cross-arm.

In Fig. l the arrows indicate the directions taken by inductive currents of discharge after the termination of a signaling impulse. Each section of the line is cleared by a discharge from its middle toward both ends and over the leak-branches at its extremities.

The time of static discharge of a conductor is foundto be about proportional to the square of its length. Thus ifone conductor is twice the length ot' another, its time oi' static discharge will be four times greater. 0f course the magnitude of static discharge is proportional to the length of line. Therefore, by providing a line with many leak-branches, the time of discharge is greatly quickened, and the magnitude of the discharge at any point will be so slight as not to interfere with primary impulses, however rapidly they may succeed one another. For example, the section between branches a and b will discharge about four times quicker than would the part of the line between branches a and c, if branch b were omitted', and it' branch b be employed, the magnitude of the discharge of the line will be only about one-half as great at branch a as when b is omitted.

As each pole upon which the line rests furnishes a leak-branch, the leakage of the line will vary as the number of leakage-poles employed, and I have found that the leakbranches may be so far increased as to prevent communication to a distant station. However, the more leak-branches there are the better will the line be cleared of inductive eieets; and it is therefore necessary to ascertain the greatest number of leak-branches that may be employed without rendering the system materially imperfect from the effects of leakage. rIhis is a matter which can only be determined empirically for each particular line, though, as above stated, generally, where ordinary poles are employed, the line may be connected with poles about one-third of a mile apart, or about every tenth pole.

It, instead of telegraph-p oles, leaks of higher resistance be employed, they may be placed much nearer together, and, in fact, if leakage IOC IIO

imperfect means for accelerating the transmission of ordinary telegraphic signals, it was only ascertained by experiment that such leaks could be advantageously employed to eliminate the effects of static induction in the trans mission of articulate speech.

In telegrapliy the signaling-currents arc fat or quantity currents, and though a large portion may be diverted by leak-branches it is a fact, and perhaps obvious, that enough will remain on line to effect the transmission of a perfect signal; but a knowledge of the fact that a telegraphic signal will be well transmitted, notwithstanding a.leakage, affords no information that the attenuated and high tensioncurrent impulses, Variable as they are iu strength, can be passed byleak-branches without rendering the reception of transmittedI speech imperfect. If the telephonie impulses were all of one strength, like telegraphic impulses, and if it were possible to assume that a telephone-line, like a telegraph-line, might be provided with leak-branches with equal success, it is not obvious that telephonie impulses, being both undulatory and variable in character-that is, in strength and time-could be transmitted. I have found, however, that weak and strong impulses can be passed by leakbranches equally well, and that variable impulses can be passed byleak-branchcs without destroying the characteristics of electrical impulses upon which transmitted sound depends.

I am aware that Mowbrays United States Patent No. 243,290 describes earth-branches as being applied to the return portion of a telephonie circuit. My invention, however,

contemplates the use of earth-branches for the direct portion of the circuit, whereby static effectsthereonmaybcdissipatcd. Leakbranches as applied by Mowbray would not serve such l l l I LCL a purpose. IIad Mowbray attached leakbranches both to the direct and return portions ofthe circuit, his invention would have resembled mine.

lVhat I claim, and desire to secure ters Patent, is-

1. The combination of a telephonie transmitter, a telephonic receiver, a main line forming that part of atelephonic circuit over which telephonie communication is eii'ccted, as distinguished from the return portion of the circuit, and a series of earthbranches distributed along the length of the direct portion of the circuit7 substantially as specified.

2. The method of preventing inductive effects upon telephonie lines from interfering with the transmission of articulate speech or sound, which consists in establishing an approximately uniform leakage along the line, which shall not be suflieiently great that it will materially weaken, divert, or dissipate the main-line signaling-impulses, substantially as specified.

3. The combination of a telephonie main line, a series ot' main-line supports insulated from the telegraph-poles, and an occasionalv support, as specified, electrically connecting the line with a telegraph-pole or its cross-arm, substantially as described.

'lhe combination of a telegraph-pole or pole and cross-arm of wood or other partial insulating material, au iron or other conducting pin set directly in the pole or cross-arm, and a main telephonie line supported by said pin without the intervention of insulating ma` terial, as specified.

5. The combinationot` an iron or other conducting pin to which a main line is immediately attached7 set in the pole or the crossarm of the pole of wood or other partial insulating material, and a lightning-arrestcr connecting said conducting pin or support to earth.

6. The combination of line-wire L, hollow pin F, a pole or pole and cross-arm forming a )artial insulator, metal piece V, plug K, and ground-wire ll'.

WTILLIAM H. ECKERT.

Vitnesses:

Wir. B. ViiNsrzn, Wir. AizNoUX. 

